Device for connecting a coaxial cable end to a contact socket

ABSTRACT

Device for connecting a coaxial cable end to a contact socket A device for connecting a coaxial cable end (2a) which may be provided with a cable end-plug (4) to a contact socket (3) comprises a further socket element (9) surrounding the contact socket (3), a seal (8) positioned between the further socket element (9) and the coaxial cable (2a), and a pressing element (11,12) which can deform the seal into contact with the coaxial cable (2a) and the further contact element (9). The device provides both a good seal, and strain relief to the completed connection.

BACKGROUND OF THE INVENTION

The invention relates to a device for connecting a coaxial cable end toa socket, and also for connecting a coaxial cable end, that is providedwith a coaxial cable plug at its end, to a contact socket that at leastpartially covers the plug. The device preferably also provides a sealedand strain relieved connection.

Various methods and devices are known for connecting coaxial cable endsto sockets, either for connecting coaxial cable ends to each other orfor introducing coaxial cables into sockets in housings. In these knownmethods and devices efforts are made not only to ensure the electricalconnection, but also to make the connection point as secure as possible.The known methods and devices for connecting coaxial cable ends tosockets include methods and devices in which the coaxial cables areprovided at their ends with coaxial cable end-plugs. These end-plugshave standard sized outer dimensions which enable standard sized socketsto accommodate a variety of different diameters of coaxial cables, sincethe plugs can than be used to make a connection between coaxial cablesof different diameters on which they are placed and a correspondingcounter-element in a contact socket of standard size. The contact socketfor the coaxial cable or end-plug may be provided either at anothercable end or in a housing such as a distribution box or the like.

As examples of the known methods and devices, there may be mentionedEP-0 023 880-A1, DE-22 38 267-C3, DE-23 25 123-B2, DE-31 41 966A1, DE-3230 473-A, DE-35 11 039-A1 or DE-35 12 952-A1 of the Applicant.

Connection plugs for coaxial cables are also disclosed, for example, inDE-84 07 987-U1, DE-84 24 169-U1 or DE-82 19 184 of the Applicant, thelatter disclosing, as does U.S. Pat. No. 4,151,364, a double-actioncoupling element for the direct connection of two cable ends.

It is also known to provide seals in the connection region of coaxialcables. DE-36 07 451-A1 of the Applicant, for example, discloses acoaxial cable end-plug in the form of connection body which can beplaced over the coaxial cable end. The connection body is provided withan outer seal for resting against the inner surface of a socket piece towhich the coaxial cable is to be connected, and an inner seal forresting against an inserted coaxial cable.

SUMMARY OF THE INVENTION

The present invention addresses the problem of making a universalconnection for a coaxial cable-end to a contact socket, in whichconnection cable-end plugs may or may not be used, while ensuring thatan excellent seal and also some strain relief are achieved in thecompleted connection.

A first aspect of the present invention provides a device for connectinga cut-back coaxial cable to a contact socket into which the coaxialcable is inserted, the device comprising:

(i) a further socket element that can be positioned, in use, to surroundthe contact socket;

(ii) a seal extending at least part of the way between the end surfaceof the contact socket and the end of the cut-back insulation on thecoaxial cable and

(iii) a pressing element which can act on the seal to deform the sealinto contact with the inner surface of the further contact element andthe outer surface of the inserted coaxial cable.

As used herein, the term a "cut-back coaxial cable" means a cable baredin the known standard way for connection to a contact socket or toanother cable. A coaxial cable comprises an outer insulating jacket, anouter conductor, an intermediate insulating layer and an innerconductor. In a cut-back coaxial cable bared in the standard way, eachof the layers surrounding the inner conductor is cut back increasinglylarger distances from the end of the cable, to reveal a section of thelayer underneath it. Thus a stepped configuration results in which theouter insulation jacket is cut back the furthest, and the innerinsulating jacket the least.

The invention also provides a method of connecting a cut-back coaxialcable to a contact socket into which the coaxial cable is inserted,using a device according to the invention, the method comprising:

(i) positioning the device over the contact socket, and

(ii) activating or moving the pressing element so that it acts on theseal to deform the seal between the inner surface of the further contactelement and the outer surface of the inserted coaxial cable.

Preferably the cut back coaxial cable end is provided with a coaxialcable-end-plug and the seal extends from the end face of the plug thatis towards the inserted coaxial cable at least as far as the cut backinsulation of the coaxial cable.

The pressing element acts on the seal to deform the seal into contactwith the inner surface of the further contact element and the outersurface of the inserted coaxial cable. Preferably the pressing elementacts on an end face of the seal (preferably the outer end face facingtowards the inserted coaxial cable), compressing the seal longitudinallyso that it expands radially into contact with the said surfaces. To thisend the other end of the seal preferably presses against a stop so thataction of the pressing element does not simply urge the seal along theinner surface of the further socket element. This stop may be provided,as a separate element or be part of other elements of the device of theinvention. For example if a cable end plug is provided it may be a stopshoulder on that cable end plug. As another example the seal may abutagainst part of the contact socket into which the coaxial cable ispositioned.

The provision of a seal positioned as defined, in conjunction with theprovision of a pressing element that deforms that seal, has a number ofadvantages. In particular an optimum seal is formed between the furthersocket element and the outer surface of the coaxial cable, so that nomoisture is able to enter the region between the contact socket and thecoaxial cable.

In one embodiment of the invention a screw thread is provided on thefurther socket element, preferably on the outer surface thereof,preferably at the free end thereof, and the pressing element is in theform of a union nut having a screw thread that co-operates with thethread on the further contact element. In one embodiment the pressingelement also comprises pressing webs which act on the end face of theseal. The arrangement is preferably such that when the union nut isscrewed onto the further contact socket the seal is simultaneouslycompressed longitudinally, by means of the pressing webs acting on theend face of the seal. The pressing webs may be integral with the unionnut, or a separate part, for example webs depending from an annularring. Where the webs are a separate part, this part may be urgedlongitudinally when the union nut is rotated, but not itself be rotated.The seal is thereby urged radially outward into sealing engagement withthe further socket element and the coaxial cable end, i.e. into all freespaces in the coupling region of the coaxial cable in the contactsocket.

In one preferred embodiment, the end surface of the further socketelement slopes inwardly, thereby providing an inwardly directedcontinuous guide slope along which the pressing webs (that arepreferably provided on the pressing element) can be guided. The pressingwebs will thereby be guided to act laterally on the seal to compress itlongitudinally, and will also be guided to press onto the outer surface(usually the plastics insulating jacket) of the coaxial cable.

In the preferred embodiment employing pressing webs acting on guideslopes at the end face of the further socket element, it is possible toarrange those pressing webs not only to compress the seal, but also atthe same time to act as strain relief elements. This is achieved byarranging the pressing webs to point in a direction opposed to thedirection of withdrawal of the coaxial cable, so that when a tensilestrain is placed on the coaxial cable, withdrawal of the cable issubstantially prevented by the pressing webs pressing onto the outersurface (usually the outer insulating jacket) of the coaxial cable.

In a particularly preferred embodiment involving the use of pressingwebs, a thrust collar is preferably provided, which is arranged betweenthe pressing webs and the seal so that the inner faces of the webs,towards the seal, act on the interposed thrust collar. In this manner itis possible to apply pressure to the entire outward facing surface ofthe seal, i.e. around a loop.

As stated above the pressing webs may be caused to press into the outersurface of the cables by acting on guide slopes on the end surface ofthe further socket element. Instead of providing guide slopes on thefurther socket element, similar guide slopes may be provided on aseparate annular element positioned between the pressing webs and theseal. Where a thrust collar is provided the guide slopes may be providedon that collar, or on an additional element.

The contact socket into which the coaxial cable is inserted, and/or thefurther socket element, may be a coupling element at a free end of asecond coaxial cable. The coupling element may, for example, couple theouter and inner conductors of the two coaxial cables. Alternatively thecontact socket may comprise a cable entry pipe to a housing of anelectrical device such as a distribution box or the like. The contactsocket may form a mechanical coupling to the coaxial cable(s) or be heatrecoverable, preferably heat shrinkable. Such contact jackets are wellknown and should be apparent to the man skilled in the art. The deviceof the present invention may include a contact socket as describedherein.

The further socket element of the device of the invention, may beplastic. It can also be equipped with an external thread and/or can beheat shrinkable at least in regions, in order to facilitate connectionto (e.g. shrinking down) onto the inserted coaxial cable end and/or ontoa housing entry pipe or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below, by way of example, withreference to the drawings, in which:

FIG. 1 is a partially cut-away view of two coaxial cables coupled toeach other, in a position in which the two coaxial cable ends have notyet been secured to each other;

FIG. 2 is a view of the union nut shown in FIG. 1 approximately alongthe line II--II of FIG. 1,

FIG. 3 is a view, corresponding to FIG. 1, of the coupling region in thesecured position; and

FIG. 4 shows the free end of the coaxial cable end 2a of FIGS. 1 and 3,that has been provided with a coaxial cable end-plug.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to all the figures, a device according to the invention,generally designated 1, for connecting two coaxial cable ends 2a and 2bcomprises a coupling-like contact socket 3 on one coaxial cable end 2b,and a coaxial cable end-plug 4 on the other coaxial cable end 2a.

The coaxial cable plug 4 has at its one end towards the cable end 2a, astop shoulder 5. This can be seen in FIG. 4. A seal 8, shown here as asealing composition sleeve, extends from the stop shoulder 5 of thecable end-plug 4, over the outer conductor 6 of the coaxial cable 2a, asfar as the cut back outer insulating jacket, designated 7, of thecoaxial cable 2a.

The contact socket 3 is surrounded by a plastics socket element 9 which,in the coupling position, projects so far over the inserted coaxialcable end 2a that the sealing composition sleeve 8 is completely coveredby the plastics socket element 9, as will be seen from FIGS. 1 and 3.

At its free end (towards coaxial cable 2a), the further socket element 9has an external thread 10 over which an internally threaded union nut 11engages.

The union nut 11 constitutes the pressing element of the invention andto that end is equipped with inwardly pointing, slightly inclinedpressing webs 12. The webs 12 rest against inwardly directed guideslopes 13 on the free end surface of the socket element 9. Between thepressing webs 12 and the sealing composition sleeve 8 there isadditionally provided an annular thrust collar 14 which rests againstthe end face of the sealing composition sleeve 8 facing out towards thecoaxial cable 2a.

The mode of operation is as follows:

The coaxial cable end plug 4 is positioned on the cut-back coaxial cableend 2a, and then pushed into the contact socket 3. The pressing elementin the form of the union nut 11 is then screwed onto the external thread10 of the further socket element 9. This causes the pressing webs 12 ofthe union nut 11 to press against the interposed thrust collar 14, i.e.to press in a direction to the right in FIG. 1. As the pressing webs 12move to the right the inward-end faces of the webs 12 come to restagainst the guide slopes 13. As screwing of the nut continues, the guideslopes 13 guide the pressing webs 12, in a sliding manner, towards theouter jacket of the coaxial cable 2a, so that not only is the thrustcollar 14 pushed further to the right but also the free ends of thepressing webs 12 are pressed into the plastics insulating jacket of thecoaxial cable end 2a, for example in the manner shown in FIG. 3. Thismeans that not only is a sealing action achieved by means of the seal 8,but simultaneously strain relief of the connection is achieved.

As shown in FIG. 1 the further socket element 9 is surrounded by a pieceof shrinkable tubing 15 and shrunk onto the coaxial cable end 2b.Instead the further socket element may itself be heat-shrinkable, atleast in regions. A socket element 9a of that construction is shown inFIG. 3, the region to be shrunk being shown by a dot-dash line.

The described exemplary embodiments of the invention can, of course,still be modified in various respects without departing from the basicconcept. For example, instead of being in the form of a sealingcomposition, the seal may be constructed as a deformable cylindricalsealing pipe, as a corrugated sealing pipe, as a combination ofcylindrical or round sealing rings and so on.

The invention similarly relates, of course, to the possibility ofcoupling in cases where a cable plug is not required. This is especiallythe case when the diameter of the coaxial cable to be coupled issufficiently large to be pushed directly into the contact socket 3. Inthis case, the seal 8 is supported on the end face of the contact socket3, and the mode of operation is otherwise the same.

We claim:
 1. A device for connecting a cut-back coaxial cable to acoaxial contact socket having a receiving end through which the coaxialcable is inserted and being electrically connected to an electricaldevice, comprising:(i) a seal extending at least part of the way betweenthe receiving end of the contact socket and the end of cut-backinsulation on the coaxial cable, (ii) a further socket elementsurrounding the contact socket, projecting at least partially over saidseal, and extending at least part of the way between the receiving endof the contact socket and the end of the cut-back insulation on thecoaxial cable, (iii) a pressing element operatively associated with saidseal for deforming said seal into contact with the inner surface of saidfurther socket element and the outer surface of the coaxial cable, and(iv) a cable end-plug on the end of the cut-back coaxial cable, saidcable end-plug mating with said contact socket, and wherein said sealextends from the end of said plug that is towards the inserted coaxialcable at least as far as the cut-back insulation of the coaxial cable.2. A device according to claim 1 further comprising a thread at areceiving end of said further socket element, and wherein said pressingelement further comprises pressing webs thereon for acting on the end ofsaid seal to deform said seal into said contact with said further socketelement inner surface and the coaxial cable outer surface.
 3. A deviceaccording to claim 2 wherein said receiving end of said further socketelement has an inwardly directed sloping surface which acts as a guideslope, and said pressing webs are configured for being pressed insliding manner over said guide slope and onto the outer surface of thecoaxial cable to deform said seal.
 4. A device according to claim 2further comprising an additional annular element between said seal andsaid pressing webs said annular element having an inwardly directedsloping surface which acts as a guide slope, and said pressing websbeing configured for being pressed in sliding manner over said guideslope and onto the outer surface of the coaxial cable to deform saidseal.
 5. A device according to claim 2 wherein said pressing element isin the form of a nut incorporating said pressing webs, said nut beingmoveable relative to said further socket element to cause said pressingwebs to act on the end of said seal.
 6. A device according to claim 2wherein said pressing element comprises a nut and said pressing webs,and wherein said pressing webs are moved longitudinally by said nut toact on said seal when said nut is moved relative to said further socketelement.
 7. A device according to claim 5 wherein said nut furthercomprises internal strew threads therein and wherein said thread at saidreceiving end of said further socket element is a screw thread on theouter surface of said further socket element which co-operates with saidinternal screw threads on said nut to effect said relative movementbetween said nut and said further socket element.
 8. A device accordingto claim 2 wherein said pressing webs point in a direction opposed tothe direction of withdrawal of the coaxial cable.
 9. A device accordingto claim 1 wherein said further socket element is an engagement couplingelement at an end of another coaxial cable.
 10. A device according toclaim 1 wherein said seal comprises a sealing composition sleeve.
 11. Adevice according to claim 1 wherein at least part of said further socketelement is formed of polymeric material.
 12. A device according to claim11 wherein at least part of said further socket element is heatrecoverable, preferably heat shrinkable.
 13. A method for connecting acut-back coaxial cable to a coaxial contact socket having a receivingend through which the coaxial cable is inserted and which iselectrically connected to an electrical device, comprising:(i)positioning the cable in a seal extending at least part of the waybetween the receiving end of the contact socket and the end of cut-backinsulation on the coaxial cable, the contact socket being surrounded bya further socket element projecting at least partially over the seal andextending at least part of the way between the receiving end of thecontact socket and the end of the cut back insulation on the coaxialcable, (ii) activating a pressing element associated with the seal todeform the seal into contact with the inner surface of the furthersocket element and the outer surface of the inserted coaxial cable,(iii) the end of the coaxial cable being provided with a cable end-plug,the end-plug mating with the contact socket, and (iv) positioning thecable and end-plug so that the seal extends from the end of the plugthat is towards the inserted coaxial cable at least as far as thecut-back insulation of the coaxial cable.